Mixing and blending system



June 30, 1931. .1. H. MoRRow MIXING AND BLENDING SYSTEM Filed OGC- 5. 1928 4 Sheets-Sheet 2 lune 30, 1931.

.1. H. MoRRow M1fx1NG AND BLNDING SYSTEM Filed oet.v s, 192s 4 sheets-sheet 5 m5 M L l- J n R j@ M m# o. N m l m M ATTORNE` June 30, 1931. 1 H MQRR0W- .1,812,604

MIXING 'AND BLENDING SYSTEM Filed Oct. 3, 19284 4 Sheets-Sheet 4 CLOSED REMOTE CONTROL ATTORNEYS 7% main/f Patented June 30, 1931 UNITED STATES PATENT OFFICE I JOSEPH HUMIHREYS MORROW, F CATASAUQUA, PENNSYLVANIA, ASSIC'rll'OIR,- TO

FULLER COMPANY, 0F CATASAUQUA, PENNSYLVANIA, .Av CORPORATION 0F PENN- sYLvANIA MIXING ANDIBLENDING SYSTEM:

Application led-ctober 3, 1928. Serial No. 310,011.

This invention 'has to do with mixing and blending pulverized or finely divided -dry materials of varying physical and chemical characteristics for the purpose of producing' an ultimate mixture having or approximating a desned predetermmed analysls, either jchemical or physical or both. More specifically the invention is concerned with a methi od by which such and blending operations may be performed, and an apparatus by which the new method .in its preferred and various modified forms may be carried out.

According to the new method, the operations of mixing and blending are carried 011 in such manner that the particles of the various materials are brought into intimate contact Without classification according to specific gravity or ineness, so that a physical mixture is produced suitable for certain chemical processes and of such characterthat chemical reactions brought about by the ap-` plication of heat, such as calcining, sintering, and fusion processes, or in solution with or Without the application of heat, are facilitated. Furthermore, the new method perv mits the'blending of two or more mixtures of materials, at least one of which will have an excess and another a deciency With respect to certain necessary ingredients, in such proportions as to produce an ultimate mixture of thoroughly mixed and blended materials of the desired analysis. y

The various steps of the new method may be performed by apparatus presently to be described in which a minimum of supervision is required, the control of the How and distribution of the various materials being automatic, although provision is made for modifying under remote control the sequence and duration of operation of the several parts of the complete system, so that correction may be made for unexpected changes in the characteristics or chemical content of the separate ingredients which go to make up the mixpurposes of illustration in connection with its application to the mixing and blending of dry cement raw materials for the dryprocess of cement manufacture, though it is to be understood that it is not limited in utility to this specific service.

In the'manufacture of Portland cement, it is essential that the raw materials be thoroughly mixed and blended before burning in order to produce sound cement of uniformly high quality. Improperly mixed raw materials not only contribute to unsoundness and low strength in cement but often delay production due to the formation of clinker rings in the kiln and to variation in feeding.

.The diflicultyin obtaining and maintaining accurate mixtures of dry materials is due to various reasons, such as the lack of uniformity in the material itself, thevariation between samplesiand the mass, changes in analysis as the materials are processed, stored and tranported, and mechanical ditliculties in bothhandling and proportioning.

Influenced largely by these diiculties, most of the newer cement plants practice the socalled wet process in order tol control the analysis within th-e necessary limits. In accordance with the Wet process, the materials are ground water and delivered as a thin liquid to correction tanks.y These tanks are usually divided into three groups. In one group the Wet materials or slurry may be deficient in one or more of the necessary ingredients, and in the second group there will be an excess of the same ingredients. These materials arethen proportioned and delivered to the third group of tanks where they are thoroughly mixed `by agitation. Although this method permits close control of the analysis, it has the disadvantage of requiring much more elaborate and complicated apparatus, and close supervision. In addition, more fuel must be burnedto drive off the Water before the material can be converted to cement clinker.

-My invention does not follow the practice of the Wet method, but takes advantage of certain characteristics of dry pulverized materials to effect a mixture in a very simple manner., In one application of the method,

however, to be described hereinafter, correction may be accomplished in a similar manner to that used in the Wet process, but this practice Will ordinarily be unnecessary. By my method, therefore the economical advantages of the dry process can be retained and an equally sound uniformly high quality cement can be made at lowervcost under more simple and convenient operating conditions.

The practice in obtaining the mixture of raw materials varies in dry process plants and depends largely upon local conditions, such as the location, composition and nature of the materials used, namely the limestone, cement rock, clay, shale,v etc. At some plants, a fairly good blend can be made in the quarry itself before crushing, while in others the materials are crushed and stored separately and the desired mixture obtained by proportioning the materials as they are Withdrawn from storage before final grinding. It is also common practice to mix the materials so that the composition is either excessive or deficient in one or more ingredient such as lime, and to control the mixture either by adding clay or shale if the lime is high, or limestone if it is low, before final grinding.

It is theoretically possible to obtain a supply of finely ground materials of the desired composition and suitable for burning byany of the practices described above, but

it will be apparent that although the entire bulk may have a proper composite analysis, it by no means follows that the materials as actually supplied to the kilns from minute to minute or from hour to hour will have the desired analysis and contact between particles. This is due to a number of factors over which the cement chemist has little or no control. For instance, the materials properly blended at the quarry may separate during crushing, milling and handling due to differences in the time of grinding between the hard and soft materials and to a natural tendency of crushed materials to classify both in storage and handling in accordance with fineness and weight. In addition, when the crushed materials are withdrawn from storage, it is almost impossible for mechanlical reasons to mix them in such manner that .although standard practice may be changed under certain conditions as described hereinafter.

While the method can be performed between preliminary and final raw grinding in plants practicing two stage grinding, it will be described in its application to the mixing and blending of finely ground materials between the mills and the kilns.

In practicing my method, I prefer to make use of the so-called Fuller-Kinyon conveying system (see Kinyon U. S. Patents Nos. 1,553,539 and 1,652,281) for the transportation and distribution of the materials, since this system has the peculiarity of transporting and discharging the materials in an aerated and fluent condition such that they assume a flat or hydrostatic level in the bins or silos with no tendency to segregate or classify according to weight or ineness. Also the transport pipe lines of this system may be interconnected to provide for any desired distribution and automatic control of material flow can be arranged in predetermined sequences as described hereinafter.

One of the factors contributing to the formation of the desired mixture in the practice of my invention is the natural tendency of dry pulverized materials, when withdrawn by gravity from storage bins or silos, to form pipes or rat holes above the discharge spouts lthroughout the entire height of the material in the bin. The materials thus discharged are the product of almost all levels from the top to the bottom of the bin as the material moves inwardly and downwardly through the rat holes rather than the lowermost material in storage.

In general, my invention involves conveying the mill stream to storage in at least three and preferably four or more bins or silos, the flow of materials into the separate bins being intermittent and in a definite sequence. This intermittent distribution is preferably under timed automatic control of the branch line valves or other distributing apparatus, operating so that the bins receive the mill Astream consecutively for short periods, each bin receiving a succession of thin flat layers of the materials. The thickness of these layers will depend on local conditions such as the diameter of the bins, the maximum normal mill stream error andthe number of bins available to serve as mixing tanks, and may vary, for example, from three inches to two feet, being modified at will by changing the rate of delivery or the duration of operation.r In order to enhance the mixture this stored material may be re-circulated and in addition, other materials such as flue dust may be blended with the mill stream and c1rculated materials.

After delivery of the mill stream to the silos has continued for some time and a number of layers have been formed in each bin, mixing additional to that accomplished by so produced is circulated and dischargedl into one bin after another, at the same time and in the same sequence as the mill stream.

Flue dust may be discharged into the bins at the same time.

The simultaneous discharge `of the mill stream, circulated material and fine dust into the same bin causes additional mixing `due to` the turbulent discharge of these fluent materials and their natural tendency to mix as they seek their level in forming the layer 1n the bin. Each layer so formed is therefore a partial mixture of the discharged materials. AAfter the materials have been circulated and the mixture is completed, they are Withdrawn and delivered to the kiln bins under the same timed automatic control of distribution toform similar thin, fiat layers in these bins which layers run together during Withdrawal by the kilnfeeders.

When the entire system is operated under its automatic control, in normal operation the primary factors contributing to the ultimate mixture are (1) the spread of the mill stream error over the number of silos avail? able dueto the alternate distribution; (2) the time interval of distribution and the rate of delivery Which govern the thickness of the layers; (3) the number of layers in the mix- 'ingvpulverized materials,

ing bins; (4) the number vof withdrawal spouts below the bins ;l (5) circulation and the number of streams of material discharging into a bin under turbulent conditions; (6) intermittent and alternate delivery' to the kiln bins and withdrawal under similar layer conditions. These mixing factors are notv arbitrary and are variable under different physical conditionsdepending upon the nature of the installatiomas will be better understood from the specific description hereinafter.

. to the kiln bins under timed automatic control in intermittent sequence. A fairly good mixture will result as the variation willbe reduced by reason of the number of kiln bins available to. receive material, the number of'v layers in each bin-r; and the thinness of the layers, all of which cooperate to produce a mixture of uniform characteristics.

ffmaterial into one bin reserved for thisvpurpose. It may then be Withdrawn and utilized in proper proportions with materials in the other storage bins to arrive at the proper composition. For example, if the material delivered to the special bin is deficient in r lime, the chemistcan'increase the lime content 1n the remamlng bins, and by proportioning the withdrawals from the several v bins a linal accuratemixture will result.

If these conditions are offrequent occurrence, the system can be arranged for correction as Well as mixing in a manner similar to that used in the Wet process. Under such conditions, at least six-mixingbins should be available and the automatic control arranged to .deliver irst to one group of three bins in the same manner as described above and then to the second three bins operating as a unit. In one group of bins a mixture will be created that will bel deficient in lime for example, While in the other group of bins` the mixture will contain an excess of lime. Vithdrawals made from these tWo groups of bins will then be so proportioned that'the filial Vcomposition will be accurate and the final 1g. 2v is a plan view showing the pipe line and in Fig. 1, Y Y

Fig. 3 is a partial wiring diagram of the valve operating circuit,

Fig. 4 is a detailed diagram of the circuit for loperating one of the automaticallypump layoutbelow thesilos shown vcontrolled pipe line valves,

F ig. 5 is a diagram of the layer composition of three successive layers in one silo, and

Fig. 6 is a schematic diagram showing a slightly modified layout of the system.

Referring first to Fig. l, four blending or correction silos are shown, hereinafter referred to as blending silos or bins designated 1to 4 inclusive. The mill stream is conveyed to these silos from the pulverizer mills 10 by the collector screw 1l delivering to the pump 1'2 connected to transport line 13. Delivery to the separate silos is under control of valves 14', 15, and 16, each valve having a suitable branch line such as that shown at 17 leading to its silo. The materials are Withdrawn from the silos preferably Athrough at least iive spouts which terminate in a common discharge pipe indicated schematically at 18. A pump is connected to each pipe arranged to deliver the material as follows.

n The pump 19 receiving material from thel withdrawn in a similar manner and are transported by pumps 25 and 26 through their common transport line 27.

lVhen circulation of the materials is desired in order to effect a more complete mixture, the materials may be withdrawn from the silos 1 to 4 inclusive by means ot' the pumps and transport lines and delivered to the silos. For this purpose, the line 21 is arranged to lead to the tops of the silos and is provided with switching valves 28, 29, by which the flow of material to the several silos may be controlled. The line 27 similarly leads to the tops of the silos and is provided with similar control valves 28', 29', 30' and i branch lines. 1

The materials `withdrawn from the silos through the lines 21 and 27 are conveyed to kiln bins, the line 21 having a control valve 31 and a branch line 32 leading to a valve 33 in the kiln transport line 34. The line 27 is similarly connected to the kiln transport line 34 at the valve 33 through a control valve 35 and a branch line 36. 'Ihere are shown the mill stream and the product stored in the four silo bins, a separate bin 39 may be provided for storing this material, which may be Hue dust for example. The flue dust is withdrawn by mechanism similar to the apparatus under the silo bins and includes a pump 40 With its transport line 4 1 which delivers the dust to anyone ofthe four silos through valves 42, 43 and 44.

As an example of the method of blending and mixing the several materials, the following is given.

Materials discharged from the mills are delivered under timed automatic control such that small quantities of material will be first discharged into silo 1 and then successively into the other three silos, whereupon the flow will be diverted back to silo 1 and the sequence repeated. At the same time a relatively small quantity of flue dust, which is usually employed in relatively small amounts will be delivered to the silos in exactly the same sequence as the mill stream.

In the rst period or interval while mill stream and flue dust are being discharged into silo 1, withdrawals of materials from that silo and silo 2 are being made by pumps 19 and 2O which deliver the materials so Withdrawn through transport line 21, branch line 32 and transport line 34 to the kiln bins under control of valves 38. These materials are discharged into four kiln bins 1'4 inclusive in sequence, each kiln bin receiving for a period one quarter as long as the period of Withdrawal from the silos. During the first period of operation, kilns bins 5' and 6 do not receive but this is taken care of in a later interval when the order of supply to these bins is 5', 6', 1', and 2'. While silo 1 is receiving mill stream and fluedust, materials are also being withdrawn from silos 3 and 4 and delivered by pumps 25 and 26 through line 27 and valves 28 to silo 1.

In the next interval of operation, silo 2 receives mill stream and flue dust and withdrawals from silos 3 and 4, while withdrawals from silos 1 and 2 are being delivered to kiln'bins 1, 2', 5', and 6'. Following this, silos 3 and 4 are successively supplied with mill stream, flue dust, and materials withdrawn from silos 1 and 2. During these periods, no materials are supplied to the kilns but withdrawals from' silos 3 and 4 are delivered back to one or the other of them depending on the interval.

In the fifth interval of operation, silo 1 receives mill stream, iiue dust, Withdrawals 'from silos 3 and 4, and Withdrawals from silos 1 and 2 which are diverted from the kiln bins to this silo. In this interval, therefore, silo 1 receives four independent streams of six materials or separate mixtures. In the sixth interval, silo 2 receives materials from the same sources and in the same manner.

In the seventh and eighth intervals, withdrawals from silos 3 and 4, respectively, are delivered to the appropriate kiln bins in sequence, While mill stream, flue dust and withdrawals fromI silos 1 and 2 are delivered to silos 3 and 4 in sequence. In the ninth to twelfth intervals, all materials are delivered to silos 1, 2, 3,v and 4 consecutively. The twelfth interval is the last in the sequence, and after that, the sequence of operations is repeated. y

It will be noted that in the method described, the silos are supplied one after another and while either of the irst pair is receiving, materials withdrawn from the second pair are supplied thereto, and vice versa. During those periods in which the kiln bins are supplied, the materials delivered thereto are withdrawn from a pair of silos, one of which is receiving. The silos employed to practice the method described are of considerably larger capacity than the kiln bins lll ' and the milling equipment used has a greater output than can be handled by the kilns, so that supply to the kiln bins may be shut olf during certain intervals, thus permitting circulation among the silos. The excess capacity of the silos and mills also makes it p ossible to set upa reserve in storage against a.

breakdown and permits the mills to be operated in periods when power charges are lowest.

lVhile the method of supply, circulation, and feeding to the kiln bins above described is highly satisfactory to effect blending and mixing of the raw materials, it. will-be understood that it is described merely as illustrative and many variations in and departures from it may be made under differing local conditions. Also it will be apparent that thev deliveries to the kiln bins are not always exactly as described since in certain intervals .when delivery to these bins would normally occur, the bins may be .still filled for one reason or another. ln that event, the

anaterials which would have been supplied to them are circulated among the silos.

ln order to make clear the character of the mixture in the different layers delivered to the silos, reference may be made to the diagram in Fig. 5, showing the composition of .the mixtures delivered to silo l in the first,

fifth and ninth intervals of operation. Bei low the main diagram is a legend graphically representing the varying composition of the materials in the mill stream and the different .1, blends. In this legend, the mill stream composition is indicated as varyingfrom minute to minute, and the materials withdrawn from the silos are in each instance of variable composition since they are Aproduced by the running together of aplurality of layers and the mixing of mill stream and flue dust with the stored materials. 4It follows, therefore, that although the materials inthe fifth and ninth layers are composite products derived from the same source, they may vary considerably in analysis. rlhe Hue dust does not vary much in composition and has beenrepresented as of the same composition throughout.

The operation of the system will be'clear by reference to Figures 3 and 4 which contain wiring diagrams showing how automatic and remote control is accomplished. In connection with these figures, itis to be borne in mind that the valves operate in groups and,

- consequently, a number of circuits can be controlled from the same source. These diagrams are limited to the essentials of the circuit and only such typical valves and operating mechanism therefor are shown as are necessary for a complete understanding of the system as a whole.

In Figure 4, there is shown a standard type of two-way valve 50, which is operated pneumatically by cylinders 51 and 52 containing pistons connected to the moving parts of the valves. The supply of air to these cylinders is controlled by valve operating solenoids 534 lity of rotating cams driven by a suitable motor 66 through reduction gearing and the gear ratios employed determine the time intervals in the sequence of operations. Two valves designated No. 1 and No. 2 switch valves and corresponding respectively to valves 31 and 35 (Fig. 1) are shown, these valves controlling the flow of material from main transport lines 21 and 27 to branch lines 32, 36, connected to transport line 34 leading to the several kiln bins. Each of the valves 3l, 35 is equipped with an opening solenoid 53 and a closing solenoid 54, by which the supply of air to the operating mechanism of the valves is controlled. The drum switch '55 is provided with a cam 57 having a projection 58 which when moved into proper position, closes the upper contact of a switch 59,-which closes a circuit through the opening solenoid 53 of No. 1 switch valve,moving this valve to open position, i. e. a position in which the branch connection is open, so as to permit material to flow from transport line 21 through the valve into the branch line 32. When the time switch has rotatedlSOo, adepression'in the cam 57 oppositethe projection 58 causes the switch 59 to close a circuit, by which energy is supplied to the opening solenoid 53 of No. 2 switch valve. With the arrangement shown in Figure 1, the operation of the valves in the manner described resultsin materials being 'delivered first from silos l and 2 to the kiln bins and then after an interval from silos 3- and 4. Each of the valves designated No. 1 and No. 2 switch valves may be'operated by remote control the operation of the cam 62, similar in construction to the lcam57 and operating a switch 63, which controlsseparate circuits through the closing solenoids 53 of the two valves.

ln Figure 3, there are shown the clrcuits for supplying current tothe solenoids of the .kiln line valve 33 and to one of the valves 38 associated with a kiln. The valve illustrated lis that over kiln No. 5. through which materials passing through valves 3l and 35 enter thev @F3-.Import line 34 Thevalve 33 to the kilns .is provided with opening and closing solenoids 53 and 54, respectively, and the opening solenoid 53 of valve 33 is connected in parallel with the closing solenoid 54 of No. 2 lswitch valve, and the closing solenoid 54 of valve 33 is connected in parallel with the closin solenoid 54 of No. 1 switch valve. With t is arrangement, it will be apparent that when No. 1 switch Vvalve or valve 31 is closed,.materials owing through the line 21 pass the valve 31 and are delivered to one or the other of the silos. When the valve 31 is closed to its banch,the valve 33 is similarly closed to its branch, and the line 32 is thus shut olf at both ends. When No. 2 switch valve or valve 35 is closed t0 its branch, the valve 33 is closed to the line 36 but open to the branch 32.

In order to simplify the diagram, the control circuit for only one of the kiln line valves is shown and this valve is provided with an opening solenoid 53 anda closing solenoid 54, the valve being opened by the action of a cani 66 in the switch 55, which cani has two surface projections. lVhen these pro'ections come into the proper position, t ey close a switch 67 which energizes the circuit which includes the opening solenoid 53 of the valve 38, and this valve is closed by means of the cam 64 in the drum switch which closes the circuit through the switch 65, which controls the closing solenoid 54 of the valve 38. The push button 68 affords means for opening the valve and permits the chemist or operator toK change the sequence of operations at a remote control point.

The valves for controlling the flow of materials into the silos operate simultaneously in groups. When materials are t be delivered to silo No. 1, the valves 14, 28 and 28' are open through their branch lines, while the valve 44 in the 'lue d ust line is closed to its branch but open yto the end of the line. If materials are to be supplied to silo No. 1

l through the lines 13, 21, 27 and 41, vlalves 14,

28 and 28 will be opened and valve 44lclosed, and this operation is accomplished by means of the cam 7 0, which operates the switch 71. When this switch is closed by the cam, current is supplied to the closing solenoid 54 of valve 44 and to the openinfr solenoids 53 of the valves 14, 28 and 28. alves 14, 28 and 28 are opened and valve 44 closed to its branch by the operation of cam 72, which controls theaction of switch 73. When this switch is closed by its cam, current is supplied to the opening solenoid 53 of valve 44 and to the closing solenoids 54 of the valves 14, 28 and 28. The circuits for each of these valves are controlled by double pole switches 74, so that the valves may be maintained in position to. prevent the flow of material into a silo, if it is desired to maintain that silo empty.

When material is to be supplied to the No.

1 bin, all of the valves 14, 28 and 28 above that bin are opened to their branches, while the main lines at and beyond these valves are closed. At the same time the valves above all the other `silos are opened but the material flows into the No. 1 silo since this is the first in the series connected to transport lines 21 and 27. Accordingly, the switch 71 controls a line which energizes the opening solenoids of all of these valves above the silos. `When it is desired to deliver material to silo No. 2, the valves 14, 28 and 28 above that silo are closed, while all the other silo valves remain open. Since under these conditions the valves 15, 29 and 29 are the first open valves reached by the 'material, all of the material passes through the branch lines of these valves and is delivered into silo No. 2.

The same situation holds true with respect to the valves 38 above the kiln bins. When material is to be delivered into kiln bin No. 1, all of the valves are opened simultaneously by the energization of their opening solenoids 53. Vhen kiln bin No. l has received the desired amount of material, the valve 38 above this bin is closed to its branch and material passes on beyond that bin, but is immediately diverted through the next valve 38 above bin No. 2. It will be understood that in all of these valves when a valve is in open position, the branch leading from the valve is open and the main line at and beyond that valve is closed.

In Figure 4, there is illustrated a schematic arrangement of one kiln bin valve 38 corresponding to valve over No. 5 bin in Figure 3. There are also shown certain supplementary circuits provided so that the system will not deliver materials to the sc-veral kiln bins after these bins have become filled. These kiln bins also have certain control circuits with lamps, which are dupli cated for various valves or groups of valves.

The valve 50 is provided with a valve position indicator switch 75 mounted on thc valve throwing lever 78 and including mcrcury tube or mercoid switches 76 and 77. When the valve is in the open position a circuit is closed through mercoid switch 76 controllin an indicator lamp 79 mounted on thc controand signal panel. This lamp may bc `a white bulls eye. When the valve is in its closed position, a circuit is closed through mercoid switch 77 and this circuit includes a lamp 80 which may also be a White bulls eye appropriately marked on the signal panel. The operation o'f the valve brings about a movement of the valve operating lever which causes the switch 75 to tilt to break the circuit through one of its mercury tubes and close the circuit through the Other.

When the material in each kiln bin reaches a desired high level, a high bin signal shown diagrammaticall at 81 is operated by the flow of materia against a paddle 82 susvided with -two sets of contacts 84 and 85.,

paddle is mounted a-mercoi-d switch 83 pro- Vhen the material level in the bin is below the paddle, the latter hangs vertically and by reason of the normally inclined position of the switch 83, the mercury therein closes the circuit through contacts 85 causing a red lamp 86 on thecontrol panel to be illuininated, indicating that the bin is in condition to receive material. When material is delivered to the bin and reaches a predetermined level, thepaddle is moved in the direction of the arrow (Fig. 4) causing the mercoid tube to tilt so as to break the circuit through contacts 85, an-d close the .cir-

I cuit through contacts 84. The circuit through contacts 84 operates thetime relay designated 87 whichl energizcs the closing solenoidv54 associated with the valve through which inaterial is supplied to the, bin, thereby shutting ott' the flow ot material .through that'val've. Then the circuit through contacts is broken, the red lamp 86 is extinguished, in-

dicating that the bin is full'. It desired a second switch similar to switch 83 may be mounted on the paddle to control a circuit to reopen the valve when the material in the bin falls below the desired level. In the circuit which includes the opening solenoid 53 of the switch valve 50 is a push button 88 by which the Valve maybe reset or positioned manually.

Ilhe time relay v87 operates only after a f 'suitable time interval, so that it functions only after the paddle 82 has beco-me stationary in a position resulting from a high level v of material in the bin. When direct current l pumps 19, 20, 25 and 26 may be provided with its own pipe line` thus permitting separate control of withdrawals from each of the silos, and return of such withdrawals to any selected silo. If it is desired to 4simplify the arrangement, all four of these pumps may be connected yto a single pipe line. In the latter event, it would probably be convenient to provide a collector screw below all of the silos discharging to a single pump. The latl ter arrangement in which all of the silos de- A liver to a common'transport line, lacks to al considerable extent the flexibility of control which is .desirable and is subject to the disadvantage that the operation of the entire system might be stopped by the failure'of a single element.

In Figure 6 there is shown a somewhat:

modified layout, in which the materials discharged from the pulverizer mills'110 are collected by a screw 111 and delivered by a pump 112 connected by a line 113 to the sev eral silos 114,115,116 and 117, which serve as blending and correction tanks. The transport line 11S/is provided with valves such as that indicated at 118 by which the How of material into the bins may be controlled in accordanceA with the procedure previously described. Below the bins 114 and-115 is a.

collector screw which receives material delivered through the spout connections 120 charged thereto are led to an inverted Y.;

spout 123, which leads to the pumps 124 andf 125. -The pump 124 is connected to a kiln bin transport line125 leading to the several kiln bins 126 under control of valves 127 while the pump 125 is connected to the Vline 128 lea-ding back to the silos under control of valves 129. Between the pipe lines 125 and 128 are pro. vided cross-over connections 130 so that the operator may use either pump for delivering materials to the kiln bins or returning ma terials withdrawn from the silos back to thc silos to eiiect further mixing. I

'The arrangement illustrated in this tigure permits the operator to use bot-h pninps simultaneously, one for conveying to kiln bins and the other for circulation of materials Jfrom storage back to storage. YAlso, with this arsliut down while the other operates the system.

Under certain conditions when the inill r1 stream erroi is relatively small, materials may be transportedv vdirectly from the mill stream pump 112 through the branch line 131 into the kiln bin transport line 125 under the control of valves 132 and'133. The valves 1" 126 may be operated in this 'system by automatic control mechanism such as the niotor driven switch 55, so that delivery to the kiln bins is in sequence and for short intervals.

In that way a. fair degree of mixture will result in the materials withdrawn from the kiln bins due to the running together of the several layers therein. In this way, themill stream error is spread over theseveral kiln bins and this error can be reduced by making the layers in each bin thin.

It will be apparent that with any of th f iu: rangement the spout 125 is provided with the -usual slide gates so that one. pump may be arrangements previouslyV described, one silo may be reserved for materials which differ widely from the desired analysis the operation may withdraw materials from this silo in proper proportions by the operation of remote control switches.

In the foregoing specification the invention is described as it would be practically applied in connection with the manufacture of cement. It is to be understood that the utility of the invention is by no means limited to that particular use, but the principles thereof may be applied in the production of mixtures ofA predetermined physical and chemical analyses incident to the manufacture of many products other than cement.

. Typical examples of such uses of the invention have been stated herein and no doubt other uses of the invention may be found hereafter. The order in whichl the various steps of the method of the invention are carried out may vary according to the use to which it is put, and the degree of uniformity in the final mixture that is desired. Accordingly, I do not desire to impose limitations on the claims herewith presented by reason of the specific description of its application herein given.

lVliat I claim:

l. A method of mixing and blending pulverulent materials which comprises delivering materials to a plurality of bins consecutively to form a series of relatively thin horizontal layers of varying analysis in leach bin, withdrawing materials simultaneously from a pair of said bins and delivering them to fa discharge bin to form a relatively thin horizontal layer therein, and varying the withdrawal to include all of said bins first mentioned in consecutive pairs.

2. A method of mixing and blending pulverulent material which comprises delivering the material to a group of bins consecutively to form a series of relatively thin horizontal layers in each bin, withdrawing material simultaneously from the bins of another group -previously filled with similar layers of the material, and alternating the delivery to and withdrawal from the bins of the two groups.

3. A method of mixing and blending pulverulent material which comprises delivering the material to a group of silos while withdrawing material simultaneously from silos of another group previously filled and delivering said material withdrawn to a receiving bin to form a relatively thin horizontal layer therein, and alternating delivery toA and withdrawal from t-he silos of the two groups. v

4. A method of mixing and blending pulverulent materials which comprises delivering the materials from sources of supply thereof into a group of bins while withdrawing materials from the bins of another group previously filled and delivering said materials to the bins of the first group, and, during such delivery to the bins of the first group,

withdrawing materials therefrom and delivering them to a receiving bin.

5. A method of mixing and blending pulverulent material which comprises delivering said material from a source of supply first to a plurality of bins in a group and then to the bins of another group, and during such delivery withdrawing material from one group and delivering it to a receiving bin and withdrawing material from the other group and delivering it to the group of bins which is receiving from said sources of supply.

6. A method of mixing and blending pulverulent material which comprises delivering the materials from a source of supply to a plurality of bins to produce a plurality of relatively thin horizontal layers of the material of varying analyses in the bins, and withdrawing and mixing portions of the contents of said bins proportioned to produce a final mixture of a desired analysis.

7. A method of mixing and blending pulverulent materials which comprises delivering the materials from sources of supply thereof to a plurality of groups of bins, the bins in each group receiving materials successively to form a plurality of relatively thin horizontal layers therein of varying analyses, withdrawing the materials from the bins of the several groups simultaneously, and mixing such withdrawals, and proportioning the withdrawals from the several jgroups of bins in such manner as to produce an ultimate mixture of a desired analysis.

-8. Apparatus for mixing and blending pulverulent materials comprising the combination of a plurality of silos, conveying means for said materials including transport lines leading to each of said silos, valves in said lines controlling flow to each of the silos, and power driven means for operating the valves in sequence to cause the materials to be delivered to the silos consecutively, said means being controllable at will to vary the sequence of delivery.

9. Apparatus for mixing and blending pulverulent materials comprising the combination of a plurality of silos, conveying means for said materials including transport lines leading to each of said silos, valves in said lines controlling flow to each of the silos, and power driven means for operating the valves in sequence to cause the materials to be delivered to the silos consecutively, said means being regulable to vary the amount in sequence to cause the materials to be delivered to the silos consecutively', and remote control means for varying the operation of said valves at will.

11. Apparatus for mixingl and blending pulverulent materials which comprises the combination of a plurality ot' silos, conveying means for delivering materials thereto including transport lines leading to the silos from a plurality of sources of supply, valves in the lines for controlling delivery to each silo, and means for operating the valves simultaneously in groups to cause delivery to the silos Iin any desiredy order from a plurality of sources of supply.

12. Apparatus for mixing and blending pulverulent materials which comprises the combination of a plurality of silos, conveying means for delivering materials thereto including transport lines-leading to` the silos from a source of supply, conveying means including transport lines inter-connecting the silos, valves controlling the. delivery to each silo, and means for operating the valves in groups to bring about deliveryto the silos in a selected order of materials from the source of supply and from other silos.

13. Apparatus for mixing and blending pulverulent .materials which 'comprises the combination of a pluralityV of' silos, conveying means for delivering materials thereto including transport lines -leading to the silos from a plurality of sources of supply,

conveying means including transport lines inter-connecting the silos, valves controlling the dellvery to each silo, and means for operating the valves in selected groups to bring about delivery to the silos in a selected order of materials from selected othery silos and sources of supply.

14. Apparatus for mixing and blending pulverulent materials which comprises the combination of a plurality of silos, conveying means for delivering materials thereto including transport lines leading to the silos from a plurality of sources ofsupply,`valves controlling deliveryto each silo, and selective operating means for the valves to bring about deliveryv to the silos in a selected order i and from selected sources of supply.

15. Apparatus, for mixing and blending pulverulent materials which comprises the combination of a plurality of silos, conveying means for delivering materials thereto j including transport lines leading to the silos from a plurality of sources of supply, conveying means including transport lines leading from each silo to'all the othersilos and to a delivery bin, valves for controlling flow to the silos and the delivery bin, and selective operating means for the valves.

16. A method of mixing and blending dry, pulverulent materials having different characteristics, which comprises delivering the materials from a source of supply in sequence Vto a plurality of silos, the delivery to each silo and withdrawing and combining materials in a continuous stream simultaneously from a plurality of layers in a silo and delivering -said materials to a receiving bin.

17. vA method of mixing and blending dry, pulverulent materials having different characteristics, which comprises delivering the materials from a source of supply in sequence to a plurality of silos, the delivery to each of said silos being for a predetermined interval to form a relatively thin, horizontal layer of materials thereinand'to spread differences in characteristics over the number of silos available, repeating the sequence of delivery to said silos to form a plurality of layers of dierent characteristics in each silo and withdrawing and combining materials in a continuous stream simultaneously from a plurality of layers from a plurality of silos nd delivering said materials to a receiving 18. A method of mixing and blending dry, pulverulent materialsv having dierent characteristics, which comprises delivering the materials in sequence to a plurality of silos and for a predetermined interval to each silo to form a relatively thin, horizontal layer of materials therein and to spread the difierences in characteristics of materials over the number of silos available, repeating the sequence of delivery to said silos to form a plurality of layers of materials of different characteristics in each silo, withdrawing and combining materials simultaneously from a plurality of layers and from a plurality of silos and delivering the withdrawn materials to a receiving bin, simultaneously withdrawing and combining materials from a plurality of layers in the remainder of the silos and returning these withdrawn materials in sequence withthe materials delivered-from said source.

19. A method of mixing and blending dry,

pulverulent materials having different characteristics, whichcomprises delivering the materials from a source of supply in sequence 4to a plurality of silos and for a predetermined interval to each of said silos to form a relatively thin, horizontal layer of materials therein and to spread the diiferences in characteristics over the number of silos available, continuously repeating the sequence of delivery to said silos to form a plurality of layers of differentcharacteristics in each silo, continuously withdrawing the materials from a plurality of layers in at least one of the silos and delivering the withdrawn material to a receiving bin, withdrawing materials from the remainder of the silos and returning these materials in sequence with the delivery of materials from said source.

21. A method of mixing and blending dry, pulverulent materials having different characteristics, which comprises delivering materials from a source of supply in sequence to a plurality of silos and for a predetermined interval to each of said silos to form a relatively thin, horizontal layer of materialsy therein and to spread differences in characteristics over the number of silos available, continuously repeating the sequence of delivery, withdrawing materials simultaneously from a plurality of layers from at least one of said silos and delivering these materials in sequence to a plurality of receiving bins and at predetermined intervals to each of said bins to form similar layers therein, at the same time withdrawing material from the remainder of the silos and returning them to the silos in sequence with materials delivered from said source.

22. A method of mixing and blending dry, pulverulent materials having different characteristics, which comprises delivering materials from a source of supply to a plurality of silos and for a predetermined interval to each of said silos to form a relatively thin, flat layer of material in each silo and to spread diiferences in characteristics over the number of silos available, repeating the sequence of delivery, simultaneously withdrawing materials from said silos and from a plurality of layers therein, combining the materials withdrawn and delivering them to a receiving bin, simultaneously? ,withdrawing materials from another group of said silos and returning these materials to the silos in sequence with the delivery of materials from said source.

23. A method of mixing and blending dry, pulverulent materials having different characteristics, which comprises delivering materials from a source of supply in sequence to a plurality of silos and to each silo for a predetermined interval to form a relatively thin, horizontal layer of materials therein and to spread differences in characteristics over the number of silos available, continuously repeating the sequence of delivery, withdrawing materials simultaneously from a plurality of layers from the silos, delivering the materials withdrawn during certain intervals to a vreceiving bin and returning the materials withdrawn to the silos during other intervals. y

24. A method of mixing and blending dry, pulverulent materials having diierent characteristics, which comprises delivering the materials from a source of supply in sequence to a plurality of silos and to each silo for a predetermined interval to :form a plurality of relatively thin, flat layers therein and to spread dierences in characteristics over the number of silos available, continuously repeating the sequenceon delivery, simultaneously withdrawing materials from.a plurality of layers in a plurality of said silos, delivering the materials withdrawn during certain intervals to a receiving bin andreturning the materials withdrawn to the silos during other intervals in sequence with the delivery of materials from said source.

2'5. A method of mixing and blending dry, pulverulent materials having different characteristics, which comprises delivering materials from a source of supply in sequence to a plurality of silos and at predetermined intervals to each silo to form relatively thin, flat layers of materials therein and to spread diierences in characteristics over the number of silos available, continuously repeating the sequence of delivery, simultaneously withdrawing materials from a plurality of layers in each of said silos, delivering withdrawn materials from at least one of said silos to a receiving bin during certain intervals, returning the material withdrawn from the other silos to the silos in sequence with the materials from said source during the same interval and during other intervals alternating the delivery to the receiving bin and return to the silos of the materials withdrawn from said silos.

26. A method of mixing and blending dry, pulverulent materials having different characteristics, which comprises delivering materials from a source of supply to a plurality of silos in sequence and for a predetermined interval to each silo to form relatively thin, flat layers of materials therein and to spread differences in characteristics over the number of silos available, continuously. repeating the sequence of delivery, simultaneously withdrawing materials from a plurality of layers and from two groups of said silos, combining the materials withdrawn from one group and during certain intervals delivering them to a receiving bin, combining the materials withdrawn from the second group and returning them vduring the same intervals to the silos in sequence with the delivery of materials from said source, during other intervals returning materials from both groups to the silos in sequence with the delivery of materials from said source,fand during still other intervals alternating the delivery to the receiving bin and the return to the silos of the materials withdrawn from the two groups.

27. A method of mixing and blending dry, pulverulent materials having different characteristics, which comprises delivering materials from a source of supply to a plurality of silos in sequence and for a predetermined time interval of each of said silos to form a relatively thin, Hat layer of materials in each silo and to spread dilerences in characteristics over the number of silos available, continuously repeating this sequence of delivery, simultaneously withdrawing materials from a plurality of layers intwo groups of said silos, combining the materials of each .group and delivering the materials withdrawn from one group to a receiving bin during certain intervals, during the same intervals returning materials from the second group to the silos in sequence with the materials delivered from the source of supply, during other intervals alternating the delivery and return of materials and delivering materials from the second group tothe receiving bin and the materials from the -rst Vgroup to the silos and during still other in tervals returning materialswithdrawn from both groups to the silos in sequence with materials from the said' source.

28. A method of mixing and blending dry, pulverulent materials having different characteristics, which comprises delivering materials from asource of supply to a plurality of silos in sequence and at a predetermined time interval to each of the silos to form relatively thin, lat la ers of materials therein and to spread di erences in characteristics over'the number of silos available, continuously repeating this sequence of delivery, simultaneousl withdrawing materials from a plurality o layers from each silo of two groups, combining the materials from each `group and delivering the materials in one group to a plurality of receiving bins, the said delivery bein made in sequence and for i a predetermined lnterval to each receiving bin to form similar layers, during the first named intervals returning the materials from the second group to the silos in sequence with the materials delivered from the source of supply, during other intervals alternating the delivery -and .return of materials by delivering the materials from the second group to the receivingbins and the materials from the lirst group to the silos and during still other intervals returning materials withdrawn from both groups to the silos in se- -quence with materials from the said source.

in sequence to a plurality of silos and at the same predetermined time intervals to each silo to form a relatively thin, horizontal layer of materials therein partially mixed by delivery at the same time, continuously repeating the sequence of delivery to said silos and withdrawing material simultaneously from a pluralityof layers from at least one of said silos and delivering the withdrawn materials to a receiving bin.

30. A method of mixing and blending dry, pulverulent materials having diEerent characteristics, which comprises delivering mate# rials from a plurality of sources of supply in sequence to a plurality of silos, the materials from said sources being delivered to each silo at the same time and for a predetermined time interval to form a partially mixed layer of materials therein and to spread differences in characteristics over the number of silos available, continuously repeating lthe sequence of delivery, simultaneously withdrawing materials from a plurality of layers from y In testimony whereof I ailix my signature. I

J QSEPH HUMPHREYS MORROW. 

